Asthma and OSA: Identifying and Treating One May Help Other

Abstract

INTRODUCTION: Asthma is an inflammatory disease of the lower respiratory tract, manifesting as intermittent constriction of the bronchial airways. Obstructive sleep apnea (OSA),-hypopnea syndrome, on the other hand is defined as the presence of at least five obstructive events per hour with associated daytime sleepiness. A relationship between asthma and OSA was noted more than 25 years ago. Multiple putative pathways for OSA aggravation of asthma exist. First, OSA could promote GERD, a well-recognized asthma trigger. Second, direct links may exist through OSA-related increase in the resistive load on lower airways imposed on an already more challenged airway system especially during sleep. This occurs via upper-airway-triggered vagally mediated bronchoconstriction, and increased bronchial responsiveness. Finally,OSA may lead to oxidative stress and inflammation in the lower airway. There is a high OSA risk in not well controlled asthma. CASE PRESENTATION: A 53yr old obese, hypertensive known asthmatic presented to us with breathlessness. He gave history of repeated hospital admissions , frequent night time arousals, excessive day time sleepiness and was a loud snorer. He had progressively worsening of symptoms inspite of appropriate treatment. On a high clinical suspicion of OSA, sleep study was performed. He had AHI index of 31.4/hr, frequent arousals 8.8/hr with minimal saturation 51% and breath with flow limitations 0.2ml/hr in non supine position. He had early REM latency but desaturations and apnenic events occurred in left position. Thus a diagnosis of severe OSA with asthma was made. Patient was started on CPAP at a pressure of 10.4 cm of water with nasal mask with oxygen 2 L/min via mask. His pre and post ABG values were as follows:- PARAMETERS, PRE CPAP, POST CPAP pCO2 , 48mm hg , 24mm hg pO2 , 58.3mm hg , 84.4mm hg Ph , 7.42 , 7.48 Patient showed dramatic improvement and is on regular follow up with no complaints since one year. DISCUSSION: Studies have shown that OSA is an independent risk factor for asthma, and OSA is more common in asthmatics than in the general population. Studies of CPAP treatment of PSG-diagnosed OSA in patients with asthma reports improved asthma outcomes hence Practitioners should be especially vigilant of OSA symptoms in unstable, poorly controlled asthmatic patients, especially when obesity is present. CONCLUSIONS: Obstructive sleep apnea (OSA) and asthma are detrimental to each othera is the conclusion of a recent review of links between the two conditions.